[element model] migrate no_leading_underscores_for_library_prefixes

Bug: https://github.com/dart-lang/linter/issues/5099
Change-Id: I03bef84eca282359a3f776870c78cad22ff9aa24
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/386728
Commit-Queue: Phil Quitslund <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>

Author: pq

pkg/linter/lib/src/rules/no_leading_underscores_for_library_prefixes.dart

@@ -5,7 +5,7 @@
 import 'package:analyzer/dart/analysis/features.dart';
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
-import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/dart/element/element2.dart';
 
 import '../analyzer.dart';
 import '../linter_lint_codes.dart';
@@ -27,7 +27,7 @@ class NoLeadingUnderscoresForLibraryPrefixes extends LintRule {
   @override
   void registerNodeProcessors(
       NodeLintRegistry registry, LinterContext context) {
-    var visitor = _Visitor(this, context.libraryElement);
+    var visitor = _Visitor(this, context.libraryElement2);
     registry.addImportDirective(this, visitor);
   }
 }
@@ -38,7 +38,7 @@ class _Visitor extends SimpleAstVisitor<void> {
 
   final LintRule rule;
 
-  _Visitor(this.rule, LibraryElement? library)
+  _Visitor(this.rule, LibraryElement2? library)
       : _wildCardVariablesEnabled =
             library?.featureSet.isEnabled(Feature.wildcard_variables) ?? false;